Preparation of basic triarylmethane dyestuffs

ABSTRACT

To prepare basic dyestuffs of the general formula ##STR1## in which A and B independently of one another represent a hetero-aromatic radical or a radical of the general formula ##STR2## compounds of the general formula 
     
         A--CH.sub.2 --B 
    
     A and B have the abovementioned meaning, 
     are oxidized with oxygen in the presence of a nucleophilic compound of the general formula 
     
         D--H 
    
     and in the presence of catalytic amounts of benzoquinones substituted by halogen or cyano or of phenanthrenequinones substituted by nitro, and in the presence of catalytic amounts of nitrogen oxides--with the exception of dinitrogen monoxide--or of substances which produce such nitrogen oxides under the reaction conditions.

The invention relates to a process for the preparation of basicdyestuffs of the general formula ##STR3## in which A and B independentlyof one another represent a hetero-aromatic radical or a radical of thegeneral formula ##STR4## in which Ar denotes the grouping ##STR5## inwhich Y represents hydrogen or non-ionic substituents and

n represents a number from 1 to 4, and

R¹ and R² represent hydrogen or alkyl, aryl or aralkyl, optionallysubstituted by non-ionic or acid groups, or

R¹ and R², together or with the ortho-position of Ar, form aheterocyclic ring, and

X⁻ represents an anion and

D denotes a hetero-aromatic radical or a radical of the formula ##STR6##in which A, B, Y, n, R¹, R² and X⁻ have the above-mentioned meaning and

G represents a bridge member of the formula

    --(CH.sub.2).sbsb.n.sub.1 --, --CH.sub.2 --Ar--CH.sub.2 --, ##STR7## in which Ar denotes aryl and

n¹ denotes 2, 3 or 4, or

G, together with the two adjacent groupings N--R¹, forms a heterocyclicring of the formula ##STR8## characterised in that compounds of thegeneral formula

    A--CH.sub.2 --B                                            VI

in which

A and B have the abovementioned meaning,

are oxidised with oxygen in the presence of a nucleophilic compound ofthe general formula

    D--H                                                       VII

in which

D denotes a hetero-aromatic radical or a radical of the formula III, IVor ##STR9## and in the presence of catalytic amounts of benzoquinonessubstituted by halogen or cyano or of phenanthrenequinones substitutedby nitro, and in the presence of catalytic amounts of nitrogenoxides--with the exception of dinitrogen monoxide--or of substanceswhich produce such nitrogen oxides under the reaction conditions.

Alkyl radicals in the formulae are to be understood as, in particular,C₁ - to C₄ -alkyl radicals. The alkyl radicals carry, for example, 1 to3 non-ionic or acid substituents. Such substituents which may bementioned are halogen, hydroxyl, C₁ - to C₄ -alkyl, cyano, C₁ - to C₄-alkoxy, C₁ - to C₄ -alkoxycarbonyl, C₁ - to C₃ -alkylcarbonyloxy,aminocarbonyl, sulpho or carboxyl.

Halogen is to be understood, preferably, as fluorine, chlorine orbromine.

Suitable aryl radicals are, in particular, optionally substituted phenyland naphthyl radicals.

Suitable aralkyl radicals are, in particular, optionally substitutedbenzyl, α- or β-phenylethyl and α-, β- or γ-phenylpropyl radicals.

These homocyclic radicals can carry, for example, 1 to 3 substituentssuch as halogen, C₁ - to C₄ -alkyl, C₁ - to C₄ -alkoxy, sulpho orcarboxyl.

The radicals R¹ and R², together or with the ortho-position of Ar, form,for example, 5-membered or 6-membered rings; together, they form, forexample, a piperidine, pyrrolidine, morpholine or piperazine ring, andtogether with the ortho-position of Ar, they form, for example, atetrahydroquinoline, indoline, julolidine, phenmorpholine,tetrahydroquinoxaline or carbazole ring.

Hetero-aromatic rings D which may be mentioned are, above all, theindol-3-yl, pyrazol-4-yl and pyrazolin-5-on-4-yl ring. The heterocyclicrings are substituted, for example, by C₁ - to C₄ -alkyl groups orphenyl.

Amongst the dyestuffs described above, those of the general formula##STR10## in which, independently of one another, R³ and R⁵ denotehydrogen, C₁ - to C₄ -alkyl, hydroxyalkyl with two or three C atoms,cyanoethyl, alkoxyalkyl with a total of three to five C atoms,alkoxycarbonylalkyl with a total of three to eight C atoms,alkylcarbonyloxyalkyl with a total of three to eight C atoms, C₁ - to C₄-halogenoalkyl, sulphoalkyl with two to four C atoms, cyclohexyl,benzyl, phenyl, phenethyl, phenyl which is substituted by halogen orC₁ - to C₄ -alkyl or -alkoxy, or sulphobenzyl and R⁴ and R⁶ denote C₁ -to C₄ -alkyl, hydroxyalkyl with two or three C atoms, cyanoethyl, C₁ -to C₄ -halogenoalkyl, alkoxyalkyl with a total of three to five C atoms,alkoxycarbonylalkyl with a total of three to eight C atoms,alkylcarbonyloxyalkyl with a total of three to eight C atoms or benzyl,or

R³ and R⁴ and/or R⁵ and R⁶ together form a pyrrolidine, piperidine,morpholine or piperazine ring which is optionally substituted by C₁ - toC₄ -alkyl, or

R³, R⁴, R⁵ and/or R⁶, together with the orthoposition of the phenylring, form a tetrahydroquinoline, indoline, julolidine, phenmorpholine,tetrahydroquinoxaline or carbazole ring which is optionally substitutedby C₁ - to C₄ -alkyl, phenyl or benzyl,

R⁷ and R⁸ represent hydrogen, C₁ - to C₄ -alkyl, C₁ - to C₄ -alkoxy,carboxyl or halogen,

n denotes an integer between 1 and 4 and E represents a heterocyclicradical of the general formula ##STR11## in which R⁹ represents H, C₁ -to C₄ -alkyl, phenyl, carboxylic acid C₁ - or C₂ -alkyl ester,carboxylic acid amide which is optionally N-substituted by C₁ - to C₄-alkyl, or C₁ - to C₄ -alkoxy or a radical of the general formula##STR12## in which n, R³, R⁴ and R⁷ have the abovementioned meaning,

can be prepared particularly easily.

Particularly preferred dyestuffs are those of the general formula IX

in which, independently of one another,

R³ and R⁵ represent hydrogen, methyl, ethyl, hydroxyethyl, propyl orbutyl,

R⁴ and R⁶ represent methyl, ethyl, sulphobenzyl or sulphoethyl,

R⁷ and R⁸ represent hydrogen, methyl, methoxy or chlorine and

E represents the radical of the general formula XI

in which

R³ and R⁴ represent methyl, ethyl or hydroxyethyl and

R⁷ represents hydrogen, methyl, carboxyl or chlorine, or

E represents the radical of the general formula X

in which

R⁹ represents hydrogen, methyl or phenyl and

R³ represents methyl, ethyl, hydroxyethyl, propyl or butyl.

The anions are derived from inorganic or organic acids and are ingeneral determined by the preparation process and any purification ofthe crude dyestuff which may be carried out. In general, the dyestuffsare in the form of zinc chloride double salts, acetates, methosulphates,ethosulphates or halides (in particular as chlorides or bromides). Theanions can be replaced by other anions in a known manner.

The quinones employed as oxidising agents can be: tetrachloro-,tetrabromo-, tetrafluoro- or dicyanodichloro-1,4-benzoquinone,tetrachloro- or tetrabromo-1,2-benzoquinone and 2-nitro-, 2,7-dinitro-or 4,5-dinitro-phenanthrenequinone. Tetrachloro- ortetrabromo-1,4-benzoquinone is preferred. The quinones are employed inan amount of 10⁻³ to 10⁻¹ mols, relative to the molar amount of thecompound VI. Instead of the quinones, it is also possible to use thecorresponding hydroquinones.

Suitable catalysts are: nitrogen oxide or nitrogen dioxide, orsubstances which release nitrogen oxides under the reactionconditions--above all in acid solvents--for example iron-III nitrate orsodium nitrite. The catalysts are used in concentrations of 1 to 20 molpercent, relative to the substrate.

The new process is carried out by a procedure in which compounds of thegeneral formula VI and compounds of the general formula VII aredissolved or suspended in a neutral or acid, aqueous or organic solventat temperatures between 0° C. and 150° C., preferably between 20° and70° C., 10⁻³ to 10⁻¹ mols of quinone, relative to the molar amount ofthe compound VI, is added, the reaction solution is mixed intensivelywith oxygen, usually pure oxygen or air, which is fed in and, in thecourse of the reaction, either 1 to 20 mol percent of nitrates ornitrites are added or a total of 1 to 20 mol percent of nitrogen oxidesis metered in. The nitrogen oxides can be metered in either with thestream of oxygen or from a separate metering device. Intensive thoroughmixing of the gas and liquid is necessary in order to achieve a highrate of reaction. It is also possible to carry out the reaction underpressure.

A procedure can also be followed in which the compounds of the generalformula VII are not already added at the start of the oxidation reactionbut only in the course thereof. It is also possible not to use thecompounds of the general formula VI as such but to form them under thereaction conditions according to the invention, by using the relevantstarting materials (formaldehyde and dialkylaniline).

Examples of suitable solvents for the oxidation are: methylene chloride,chloroform, carbon tetrachloride, chlorobenzene, dichlorobenzene,benzene, toluene, xylene, cumene, acetic acid, propionic acid, lacticacid, dichloroethane, methanol, ethanol, propanol, isopropanol, butanol,glycol, methylglycol, dimethylglycol, tetrahydrofurane, dioxane, ethylacetate, dimethylformamide, N-methylpyrrolidone, acetone or mixturesthereof. The reaction can also be carried out in aqueous solution orsuspension or in a mixture of water and water-miscible solvents. The pHvalue of the reaction solution should be in the neutral to acid range,depending on the dyestuff. The acid pH range between pH 1 and pH 4 ispreferred. The following examples illustrate the invention.

EXAMPLE 1

76.2 g of 4,4'-bis-(dimethylamino)-diphenylmethane, 36.3 g ofdimethylaniline, 6 g of chloranil and 600 g of glacial acetic acid aretreated intensively with air at 40° C. In the course of the reaction,which lasts about 24 hours, a total of 1.2 g of a mixture of nitrogenmonoxide and nitrogen dioxide, produced by treating sodium nitrite withsulphuric acid, is uniformly metered into the mixture. When the reactionhas ended, the reaction solution contains crystal violet in 87% yield.After distilling off the glacial acetic acid, the residue is dissolvedin 500 g of water at 80° C. After filtering the solution, the dyestuffis precipitated by adding sodium chloride. Yield: 101 g.

Similarly good results are obtained if instead of the nitrogen oxides,2.5 g of sodium nitrite of 2.5 g or iron-III nitrate are uniformly addedduring the atmospheric oxidation.

EXAMPLE 2

93 g of 4,4'-bis-(diethylamino)-diphenylmethane, 36.3 g ofdimethylaniline, 6 g of chloranil and 600 g of glacial acetic acid aresubjected to intensive gassing with air at 40° C. A total of 1.2 g of amixture of nitrogen monoxide and nitrogen dioxide, produced by treatingsodium nitrite with sulphuric acid, is uniformly metered into themixture in the course of the reaction. When the reaction has ended, thereaction solution contains the dyestuff of the formula ##STR13## in 82%yield.

The following diphenylmethanes and compounds of the general formula VIIcan be oxidised to give triarylmethane dyestuffs by the processaccording to the invention:

    ______________________________________                                                               Compound of                                            Example                                                                              Diphenylmethane the formula VII                                        ______________________________________                                        3      4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR14##                                             4      4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR15##                                             5      4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR16##                                             6      4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR17##                                             7      4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR18##                                             8      4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR19##                                             9      4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR20##                                             10     4,4' -Bis-(dimethyl- amino)-diphenylmethane                                                    ##STR21##                                             11     4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR22##                                             12     4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR23##                                             13     4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR24##                                             14     4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR25##                                             15     4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR26##                                             16     4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR27##                                             17     4,4'-Bis-(dimethyl- amino)-diphenylmethane                                                     ##STR28##                                             18     4,4'-Bis-(diethyl- amino)-diphenylmethane                                                      ##STR29##                                             19     4,4'-Bis-(diethyl- amino)-diphenylmethane                                                      ##STR30##                                             20     4,4'-Bis-(diethyl- amino)-diphenylmethane                                                      ##STR31##                                             21     4,4'-Bis-(diethyl- amino)-diphenylmethane                                                      ##STR32##                                             22     4,4'-Bis-(cyano- ethylethylamino)- diphenylmethane                                             ##STR33##                                             23     4,4'-Bis-(cyano- ethylethylamino)- diphenylmethane                                             ##STR34##                                             24     4,4'-Bis-(cyano- ethylethylamino)- diphenylmethane                                             ##STR35##                                             25     4,4'-Bis-(dimethyl- amino)-2,2'-dimethyl- diphenylmethane                                      ##STR36##                                             26     4,4'-Bis-(dimethyl-  amino)-2,2'-dimethyl- diphenylmethane                                     ##STR37##                                             27     4,4'-Bis-(dimethyl- amino)-2,2'-dimethyl- diphenylmethane                                      ##STR38##                                             ______________________________________                                    

EXAMPLE 28

A mixture of 108.9 g of dimethylaniline, 12 g of paraformaldehyde, 600 gof glacial acetic acid and 6 g of chloranil is warmed to 60° C. for 2hours. Thereafter, the reaction mixture is cooled to 40° C. and thensubjected to intensive gassing with air. A total of 1.2 g of a mixtureof nitrogen monoxide and nitrogen dioxide is uniformly metered into themixture in the course of the reaction. When the reaction has ended, themixture is worked up as described in Example 1. 95 g of crystal violetare obtained.

I claim:
 1. In the preparation of a basic dyestuff of the formula##STR39## in which R³ and R⁵ each independently is hydrogen, C₁ - to C₄-alkyl, hydroxyalkyl with two or three C atoms, cyanoethyl, alkoxyalkylwith a total of three to five C atoms, alkoxycarbonylalkyl with a totalof three to eight C atoms, alkylcarbonyloxyalkyl with a total of threeto eight C atoms, C₁ - to C₄ -halogenoalkyl, sulphoalkyl with two tofour C atoms, cyclohexyl, benzyl, phenyl, phenethyl, phenyl which issubstituted by halogen or C₁ - to C₄ -alkyl or -alkoxy, orsulphobenzyl,R⁴ and R⁶ each independently is C₁ - to C₄ -alkyl,hydroxyalkyl with two or three C atoms, cyanoethyl, C₁ - to C₄-halogenoalkyl, alkoxyalkyl with a total of three to five C atoms,alkoxycarbonylalkyl with a total of three to eight C atoms,alkylcarbonyloxyalkyl with a total of three to eight C atoms or benzyl,or R³ and R⁴ and/or R⁵ and R⁶ together form a pyrrolidine, morpholine orpiperazine ring which is optionally substituted by C₁ - to C₄ -alkyl, orR³, R⁴, R⁵ and/or R⁶, together with the ortho position of the phenylring, form a tetrahydroquinoline, indoline, tulolidine, phenmorpholine,tetrahydroquinoxaline or carbazole ring which is optionally substitutedby C₁ - to C₄ -alkyl, phenyl or benzyl, R⁷ and R⁸ each independently ishydrogen, C₁ - to C₄ -alkyl, C₁ - to C₄ -alkoxy, carboxyl or halogen, ndenotes an integer between 1 and 4, ##STR40## R⁹ is H, C₁ - to C₄-alkyl, phenyl, carboxylic acid C₁ - or C₂ -alkyl ester, carboxylic acidamide which is optionally N-substituted by C₁ - to C₄ -alkyl, or C₁ - toC₄ -alkoxy or a radical of the formula ##STR41## R¹⁰ and R¹¹ eachindependently is methyl, ethyl or hydroxyethyl, the steps comprisingoxidizing a compound of the formula ##STR42## in the presence of anucleophilic compound of the formula

    E--H,

in the presence of quinone oxidizing agent with a catalyst comprisingnitrogen oxide or compound forming it selected from the group consistingof nitrogen monoxide, nitrogen dioxide, sodium nitrite or iron-IIInitrate.
 2. A process according to claim 1, wherein the compound beingoxidized is of the formula ##STR43## the nucleophilic compound is of theformula

    E--H,

the nitrogen oxide or compound forming it is nitrogen monoxide, nitrogendioxide, sodium nitrite or iron-III nitrate, and the end product is ofthe formula ##STR44## in which R³ and R⁵ each independently is hydrogen,C₁ - to C₄ -alkyl, hydroxyalkyl with two or three C atoms, cyanoethyl,alkoxyalkyl with a total of three to five C atoms, alkoxycarbonylalkylwith a total of three to eight C atoms, alkylcarbonyloxyalkyl with atotal of three to eight C atoms, C₁ - to C₄ -halogenoalkyl, sulphoalkylwith two to four C atoms, cyclohexyl, benzyl, phenyl, phenethyl, phenylwhich is substituted by halogen or C₁ - to C₄ -alkyl or -alkoxy, orsulphobenzyl, R⁴ and R⁶ each independently is C₁ - to C₄ -alkyl,hydroxyalkyl with two or three C atoms, cyanoethyl, C₁ - to C₄-halogenoalkyl, alkoxyalkyl with a total of three to five C atoms,alkoxycarbonylalkyl with a total of three to eight C atoms,alkylcarbonyloxyalkyl with a total of three to eight C atoms or benzyl,or R³ and R⁴ and/or R⁵ and R⁶ together form a pyrrolidine, morpholine orpiperazine ring which is optionally substituted by C₁ - to C₄ -alkyl, orR³, R⁴, R⁵ and/or R⁶, together with the ortho position of the phenylring, form a tetrahydroquinoline, indoline, julolidine, phenmorpholine,tetrahydroquinoxaline or carbazole ring which is optionally substitutedby C₁ - to C₄ -alkyl, phenyl or benzyl, R⁷ and R⁸ each independently ishydrogen, C₁ - to C₄ -alkyl, C₁ - to C₄ -alkoxy, carboxyl or halogen, ndenotes an integer between 1 and 4, E is a hetero-aromatic radical ofthe formula ##STR45## and R⁹ is H, C₁ - to C₄ -alkyl, phenyl, carboxylicacid C₁ - or C₂ -alkyl ester, carboxylic acid amide which is optionallyN-substituted by C₁ - to C₄ -alkyl, or C₁ - to C₄ -alkoxy or a radicalof the formula ##STR46##
 3. A process according to claim 1, in whichR³and R⁵ each independently is hydrogen, methyl, ethyl, hydroxyethyl,propyl or butyl, R⁴ and R⁶ each independently is methyl, ethyl,sulphobenzyl or sulphoethyl, R⁷ and R⁸ each independently is hydrogen,methyl, methoxy or chlorine, E is ##STR47## R¹⁰ and R¹¹ eachindependently is methyl, ethyl or hydroxyethyl, R⁷ is hydrogen, methyl,carboxyl or chlorine, R¹² is methyl, ethyl, hydroxyethyl, propyl orbutyl, and R¹³ is H, methyl or phenyl,the quinone comprises tetrachloro-or tetrabromobenzoquinone, and the catalyst comprises a catalytic amountof at least one of nitrogen monoxide and nitrogen dioxide.